Enable gdb pretty printing for libstdc++

gdb 7.0 added support for python pretty printers, libstdc++ provides
python pretty printers but they are not loaded by default on LinuxMint
18. Load them but only for this distro as upstream Debian enables them
by default and loading them multiple times will throw an exception.

gdbinit

@@ -1,2 +1,13 @@
 set print pretty on
 set auto-load safe-path ~/
+# Enable C++ std pretty printing in LinuxMint 18.X
+# https://sourceware.org/gdb/wiki/STLSupport
+python
+from platform import linux_distribution
+distro = linux_distribution()
+if 'LinuxMint' == distro[0] and '18' in distro[1]:
+    from sys import path
+    path.insert(0, '/usr/share/gcc-5/python')
+    from libstdcxx.v6.printers import register_libstdcxx_printers
+    register_libstdcxx_printers(None)
+end